Pumping mechanism



APll 16, 1957 l. c.JENN1NG s 2,788,745

y PUMPING uEcHANIsu Filed July 27, 1950 '3 sleetysheet 1 l. C. JENNINGS PUMPING MECHANISM April 16, 1957 v:s sneetsfsheet 2 Filed July 27, 1950 ffy/hg 6. Jam/)5w April 16, 1957 l. c. JENNINGS 2,788,745

PUMPING MECHANISM 3 sheets-sheet :s

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United States Patent O PUMPING MECHANISM Irving C. Jennings, South Norwalk, Conn.

Application July 27, 1950, Serial No. 176,103

14 Claims. (Cl. 10S- 6) This invention relates primarily to vacuum heating systems and -to pumping and associated equipment used therein. The invention is in the nature of an improvement upon the apparatus disclosed in U. S. Reissue Patent No. 15,637, granted to me on June 26, 1923, and U. S. Patent No. 1,567,148, granted to me on December 29, 1925. Certain features are also useful apart from vacuum heating systems.

The patents referred to disclose broadly the separation under vacuum of the returns from a heating system, removing air and thus creating a vacuum with a pump of the liquid ring type in which a liquid ring or seal serves both as an air propelling means and as a cooling medium, while returning the condensate separately, directly back to a hot well or boiler by means of a separate water pump. The patents referred to show the water pump and the air pump rotors fast upon a common shaft and driven by a single motor, but apparatus in which air and water pumps are provided with separate driving motors are also commercially well-known.

Ihe described cycle of operations has many advantages. The water is handled only once. The back pressure of the boiler or the hot well is only opposed to the water discharged and not to the air, the large quantity of air removed being delivered to atmospheric pressure without back pressure. This represents an important economy because the water returned to the boiler or hot well constitutes only a fraction of the total volume of fluid handled.

The apparatus shown in the patents is considerably complicated by the fact that pipes or manifolds have to be supplied between the tank and the water pump and between the air pump, its separator and the atmosphere. Means must be provided for a constant sealing for the air pump. A large and cumbersome base has to be built and accurately machined to support all the structure and the various manifolds so that they can be assembled readily.

Because the passages in the water leg of the water pump are necessarily restricted, the receiving tank has to be considerably above the elevation of the pumps, and this makes the returns into the receiving tank relatively high above the oor. In many cases this requires the use of an accumulating tank for the returns, which may come in near oor level, and these returns have to be lifted into the receiving tank with consequent reduction of the vacuum.

The water and air pumps are controlled respectively by a oat switch operated by the water in the receiver and a vacuum regulator to maintain the desired vaccum in the receiver. When the air pump is shut down the seal water in the receiver lloods the air pump. When operation of the air pump is resumed this water is discharged by the air pump with some noise, and in some cases it actually fills up the air separator on top of the receiver and spits out to the atmosphere., In some models of this type, particularly where separate drive motors for the pumps have been used, a solenoid valve Patented Apr. 16, i957 has been provided to turn olf the seal water supply when the air pump is stopped, but these valves have often failed to operate satisfactorily because they have become grnmed up by pipe fitting compound, rust and other dirt which is usually present in heating system returns.

When the air pump is provided on the same shaft as the condensate return pump its capacity is necessarily limited by the fact that it can only turn at the same speed as the condensate return pump. Such limitation of speed prevents a large Vacuum pump of the liquid ring type from operating elciently. When the speed is stepped up for the benefit of the vacuum pump the condensate pump will take excessive power. Also, when air alone is being handled waste of power results due to the hydraulic friction of the water pump although not handling condensate.

It has become increasingly important on high vacuum installations to increase the air capacity, and some of these installations, prior to the present invention, have been made to include piped up units with separate air and water pumps and piping between the receiving tank, the air separator, and the separate pumps, all of which is expensive and takes up much space.

The present invention includes among its objects the overcoming each yof the foregoing diiculties.

It is a feature of the invention that a hydro-turbine vacuum pump of the type in which a Water seal is made to serve both as an air propellant and as a cooling medium, is made to sit in Water in the separator, and is provided with a submerged direct inlet passage so that some of the sealing water supplied may be drawn from the separator and returned to the separator. Because this water is not drawn through the air passages of the air pump with the air, friction is reduced and the eiliciency of the air pump is increased. This feature may also be employed very advantageously apart from vacuum heating -systems as, for example, in connection with pumps of the type referred to when used as compressors.

It is a further feature that a supply conduit for conducting air from the upper part of the receiver to the vacuum pump inlet is made to pass down through the water in the bottom of the receiver and is provided with an opening through which seal make-up water may enter and become entrained for delivery to the liquid ring of the vacuum pump.

It is still another feature that a check valve is provided in the supply conduit which feeds air from the receiver to the vacuum pump. When the vacuum pump stops, the separator, the pump and the supply conduit back to the check valve all stand at atmospheric pressure, but the supply conduit in back of the check valve stands at a lower pressure, and there is no tendency, therefore, for water from the receiver to ow into the vacuum pump. The check valve is made readily accessible for cleaning or repair.

It is a further feature that a novel centrifugal Water pump is provided, adapted to be set at the level of the receiver bottom to permit very low returns. The pump is supplied through an unobstructed casing extension of large ow capacity, provided with a centripetal air collecting space in back of the motor, and means for conducting the collected air and small amount of water leaking past the sealing ring back to the receiver.

A further feature resides in the provision of a novel strainer adapted to be inserted through either of tWo opposite walls 0f the receiver and to be supported by the walls jointly. The strainer desirably comprises a pipe or tube formed with a multiplicity of perforations that the strainer can be cleaned in place through its open end when the wall opening in which it is supported is uncovered. Y

Vtank is partitioned to ydivide it inte a receiverl and two distinct separators, provision being made for connecting one or/two condensate pumps directly to the receiver, and for mounting aA vacuum pump inV each separator or in only one of them, as desired.

Connections are also provided for enabling one or more 'large capacity vacuum pumps to have their intakes connected onto the receiver and their discharge pipes connected to deliver into the separators.

Other obiects and advantages will hereinafter appear.

In the drawing forming part of this specication:

FigureV l is a fragmentary plan View partly' broken away of a receiver, separator and pump assembly with certain optional equipment shown in broken lines;

Figure 2 is a fragmentary View in side elevation of the assembly of Figure l but with the optional parts omitted;

' Figure 3 isV a fragmentary sectional viewv taken upon the section line 3 3 of Figures l and 6, looking in the 'direction of the arrows;

Figure 4 is a fragmentary sectional view taken upon the 'line 4-4 of Figure l, looking in the direction of the arrows;

Figure 5 is a fragmentary sectional view taken upon the line 5 5 of Figure l, looking in the direction of the arrows; Y

Figure 6 is a fragmentary sectional view taken upon the line 6 6 of Figure l, looking in the direction of the arrows; Y Y

Figure 7 is a sectional view taken upon the line 7 7 of Figure 6, looking in the direction of the arrows; and

Figure 8 is a fragmentary sectional view taken upon the line 8 8 of Figure l, looking in the .direction of the arrows.

The drawing illustrates a practical and advantageous embodiment of the invention. The illustrative apparatus comprises a closed tank 1 of generally rectangular form. The tank is divided by vertical partition walls 2 and 3 to divide oh separators 4 and 5 from the main body of the tank which'constitutes the receiver 6. The receiver and separators are provided side by side, at a common level, and each separator has external walls in common with the receiver. The partition walls 2 and 3 extend from oor to cover Vof the tank 1 so that the separators may be closed off completely from the receiver and maiutained at a dilerent pressure from the receiver.

The returns from a vacuum heating system are delivered to the receiver by a return conduit 7 which terminates in a liange secured to the tank by bolts 13. The opposite walls 8 and 9 of the tank 1 are formed with inwardly projecting flanges l0 and Il 4in, which a tubular strainer 7a is removably supported. The walls 8 and 9 and the flanges lo and Il! are identical in construction so that the pipe 7 can be secured to the wall 8 or the'wall 9, as desired. As shown in the drawing, the openingthrough the wall 8 is covered by a closure member 14 which is Y. secured to the wall S by suitable means, such as bolts 1S.

The flange 12 and the closure plate i4 are adapted to beY interchangeably connected to the walls 8' and 9. The

Vtubular strainer 7a provides a screen of large area eX- tending completely across thevtop. of the tank, which can be cleaned in place simply by removing Jthe closure plate 14. It is held by being coniiued between the conduit 7 and the closure plate 14 and can, therefore, be very conveniently removed for servicing or replacement, after `removal of the closure plate 14,V in case it becomes damaged.

Although two separators 4 and S are illustrated andV would usually be present in the illustrative structure, they are'not necessarily both put to use, since the simplest unit,

l Y would comprise a single vacuum pump 16 and a single water pump 17.

The separator 4 is connected to the atmosphere near the top through a pipe 18. Insterted in the separator 4 is a standard rotary vacuum pump 16 in which a ring of water serves as an air propelling means and as a cooling medium for the pump. This pump'is shown in crossscction in Figs. 6 and 7. Y

The pump is driven .by aV motor 19 and comprises a circular, vaned, rotor 20, which isA made fast upon the motor shaft 21. Air enters theY pumpy through a; passage 22 which,communicatesY with inlet openings 23. The round multi-blade rotor' 20' revolves freely in an elliptical casing 24, which ispartiallylled with water. The curved rotor blades project radially from the rotor hub, and form with the side shrouds aseries of pockets or buckets around the periphery. The rotor revolves at a speed high enoughjto throw the liquid out from the center byA centrifugal force, resulting in aY solid ring 25 oi liquid revolving in the casing at the'same speed as the rotor, butvr following the ellipticalv shape. of the casing. This alternately forces the liquid to enter and' recede fromV the buckets in the rotor at high velocity.

Asany selected' chamber formedJ between successive vanes travels in communication with one of the stationary inlet ports 23, the water is forced to recede from the center and is, therefore, caused to suck air from the inlet port into the chamber. YAs it travels in. communication with an outlet port 26`however, the water contained in it is forced in toward the center and hence cxpels the air to the outlet port. Y

The airV received by the. pump at sub-atmospheric pressure is compressed to atmospheric pressure and discharged through a passage 27 to the upper part of the separator 4, whence it is allowed to escape t0 the titulos-V phere freely through the discharge pipe 18'., The air pump is partially submerged in water 28 contained in the separator. This water is delivered to the separator by the pump I6, as will be. explained'.

The water isV maintained at a desired level by means of a ball oatl valve 29, the details of which are best illustrated in Figs. l and 3. The entire valve mechanism including the float is desirahly carried by a fitting 30 which is secured over openings 31 and 32 which communicate, respectively, with the separator 4 and with the receiver 6. Thertting 30 is formed with a passage 33 for conducting surplus water back Yfrom the separator 4 to the receiver 6. The fitting 30 includes an extension 34, which projects through the opening 31, and into which the passage 33 extends. The upper wall of. the-projection 34 is formed; with a port 3S which is adapted to be closed by a slide valve 36.

The. valve 36 is slidahly mounted in ears 37 which are desirably integral with the tting 30. A float 38 is carried by a forked stem 39, which stem is connected through a pin 40 with the valve 36. The stem 39 is pivotally mounted upon a pin 41,l which pin is supported in bosses 42 of the fitting 30. 'Since the separator is maintained at a higher pressure than the receiver, the water ows freely through the passage 33 whenever the valve 36 is lifted oiits seat. Because of the pressure difference, it is important'that the water level be maintained above the port 35, so that air may have no opportunity to tlewfrom the separator into the receiver through the port.

The pump takes air from near the top of the receiver 6 through a pipe or conduit 43. Provision is made both' enseas so that the air enroute to the air pump is caused to arrive at the pump intake mixed with make-up water. Beyond the orice 44 the conduit 43 again rises and extends out through the receiver wall 8 and into a chamber 45 which is formed in a side extension 46 of the pump casing. The chamber 45 communicates directly with the pump intake. Within the chamber a fitting 47 is secured upon the outer face of the receiver Wall 8 in position to cover the end of the conduit 43. The tting 47 is provided with a port 48, which port is surrounded by a valve seat. A check valve 49 tends to close the port 4S, the valve being carried by the arm 50 which is pivotally mounted through a pin 51 upon stationary ears 52. The ears are desirably made integral with the iitting 47.

The check valve 49 is made accessible for cleaning or repair by providing an opening 46a in the casing extension 46, and a removable closure 46b therefor. The closure may be removably secured in place in any convenient manner, as by means of bolts or screws 46c.

The fact that the air en route to the air pump is caused to pick up water in the conduit 43 causes water to be constantly added to the water ring 25 of the pump. The water added to the ring necessarily displaces water already present, causing it to be discharged from the air pump into the receiver.

Since the ring water tends to become heated by the compressing action of the pump, it is desirable that it be continually replenished or displaced by fresh water. The water transmitted from the conduit 43 has a tendency to eiectuate this purpose. It is not the most desirable means of providing for the make-up water for the pump because this Water not only has to be Withdrawn from the receiver in a region of comparatively low pressure and discharged to the separator at atmospheric pressure, but also it causes restriction as it comes in with the air in the air passages. The size of the orifice 44 is so chosen, therefore, that only enough water is picked up in the conduit 43 to take care of the heat of compression. Additional water required for sealing and make-up is provided by another expedient which consists in recirculating Water from the air separator through the pump and back to the air separator.

In order to effectuate the latter purpose, the pump casing is provided with a water admission orilice 53, which lets directly into the pump through a passage 22. The orice 53 stands constantly submerged so that water is continually drawn in through it from the lower part of the separator, and water displaced from the ring is continually returned through the discharge passage 27 to the separator.

The pump 16 has been referred to above as a standard pump. Two important exceptions should, however, be noted. The side extension 46 of the casing and the orice 53 are specially provided for the purpose of the present invention and are new.

The condensate removal pump 17 is a centrifugal pump. It is driven by a motor 54 and comprises an impeller 55 which is made fast upon a reduced end portion of the motor shaft 56. The impeller has close clearance with forward and rear sealing rings 57, which are supported, respectively, in a forward or lower casing member 58, and in a rear or upper casing member 60. The rotor is formed with a central opening 59 through which Water is admitted to the pump. The rotor is spaced from the rear casing member to provide an air collecting space 61 between the rotor and the casing. The forward casing member is provided with a wide unobstructed side extension 62 which is of large iiow capacity, and which is directly connected to a side of the receiver near the lower end thereof by any suitable means such as screws 63.

The rear sealing ring 57 is adapted to restrict the passage of water, but it passes more freely than water the the rear casing member. A seal 66 is provided for sealing the space between the rear casing member 60 and the shaft 56. A compression coil spring 67 bears at one end against the rotor 55 and at the opposite end against a anged sleeve 68 through which pressure is applied to the seal. A conduit 65 places the chamber 64 in communication with the receiver 6, and serves to conduct back to the receiver air and water which have passed the rear seal ring 57.

The pump 17 may be disposed either vertically or horizontally, but the vertical disposition is preferred because it enables the pump to operate with a lower water level in the receiver. The returns go directly into the bottom of the impeller 55 without any restriction whatever. Any air which would interfere with the action of the centrifugal pump is collected in the centripetal space and escapes past the upper sealing ring 59 for return through the pipe 65 to the receiver. The vented pipe' 65 relieves the seal 66 of excessive pressure.

Heretofore pumps for this kind of service have had to have' their inlets submerged about a foot or more in order to have enough positive head at the impeller eye to operate satisfactorily. This pump will operate with hot condensate under high vacuum with a water level practically down to the center line of the impeller 55. This construction makes possible a very low receiver tank of small dimensions.

An additional air pump 16a may be provided in association with the separator 5. The air pump 16a, its mounting, connections .and mode of operation will all desirably be exactly the same as for the pump 16, so that no detailed description is considered necessary.

An additional water pump 17a may also be provided when required, the pump construction and mounting being desirably the same as those of the pump 17.

Ball float switches 69 and 7G are provided for controlling the starting and stopping of the condensate pumps according to the level of the condensate accumulated in the receiver. The construction and principle of operation of these devices is conventional and is well understood, so that no detailed showing or description is thought necessary.

A vacuum regulator 71 (see Fig. 2) is provided to start the air pumps when the vacuum falls below a predetermined value. The construction and operation of vthis device is conventional and well understood, and no detailed 'showing or description is, therefore, thought necessary.

Provision is made for the addition of one or more large capacity air pumps, one at either of the remaining free sides of the receiver. One such pump is shown in dot and dash lines at 72. The pump is mounted in common with its drive motor 73 upon a base 74, the assembly constituting a standard large capacity air pump unit. The principle of operation of the pump is the same as that of the pump 16, but the capacity of the pump 72 is greater. Since the pump 72 does not stand in water, make-up and cooling water are furnished to it through a conduit 75 which extends down from the top of the receiver through the water in the bottom of the receiver, and which is provided with a water inlet orifice 76 in the submerged portion of its length. The conduit is carried by a collar 77 which is suitably secured to the receiver wall 78.

The conduit 75, externally of the receiver, includes a check valve 79 for assuring that the pump inlet will be maintained at a higher pressure than the inlet end of the conduit 75 when the pump is stopped.

rIhe pump 72 has no separator, but it utilizes the separator 4 of the pump 16. The discharge of the pump 72 is transmitted through a conduit 80 to the separator 4. In the separator 4 the water and air delivered from the pump 72 are separated, the air being discharged to the atmosphere through the discharge conduit 18 and the air collected in the space 61to a rear chamber 64 of i5 water being accumulated in the separator 4 and returned air pump of the liquid ring type in which a rotating water ring is employed which serves both as a gas and vapor impelling means and as acooling medium, said pump being arranged to pump gas, vapor and some liquid from the receiver and to discharge into the separator, an air intake conduit for said pump comprising a pipe for withdrawing gas and vapor mixed with water from the receiver, so that fresh water will be supplied to the seal and the used water caused to be progressively discharged tothe separator, a check valve disposed in said conduit, means for effecting a regulated return of discharge water from the separator to the receiver such that the water level in the receiver is maintained at a substantially constant level, the air pump being sufficiently submerged in the separator to seal said check valve against the admission of air when the pump is idle, and said pump having a submerged Water inlet in the bottom of the separator for causing replacement water from a source at atmospheric pressure also to be supplied to the pump directly from the separator, and for causing a predetermined useful amount of water to be contained in the pump at starting.

8. In a vacuum heating system, in combination, a receiver maintained under vacuum, an air separator open to the atmosphere, a rotary air pump of the liquid ring type in which a rotating water ring is employed which serves both as a gas and vapor impelling means and as a cooling medium, said pump being arranged to pump gas, vapor and some liquid from the receiver and to discharge into the separator, an air intake conduit for said pump comprising a pipe for withdrawing gas and vapor mixed with water from the receiver, so that fresh water will be supplied to the seal and the used water caused to be progressively discharged to the separator, a check valve disposed in said conduit, means for effecting a regulated return of discharge water from the separator to the receiver such that the water level in the receiver is maintained at a substantially constant level, the air pump being submerged at a predetermined depth in the separator suicient to seal the check valve aginst the admission of air to the receiver when the pump is idle, and said pump having a submerged water inlet in the bottom of the separator for causing replacement water from a source at atmospheric pressure also to be supplied to the pump directly from the separator, and for causing a predetermined, useful amount of water to be contained in the pump at starting, and at least one water removing pump, independent of the air pump, attached directly to the receiver and communicating directly therewith.

9. In a vacuum heating system, in combination, a closed tank partitioned to provide a receiver maintained under vacuum, a plurality of air separator compartments open to the atmosphere, said receiver constructed to facilitate direct attachment of a plurality of water pumps and a plurality of air pumps, at least one water removing pump attached directly to the receiver and communicating directly therewith, at least one rotary air pump of the liquid ring type in which a rotating water ring is employed which serves both as a gas and vapor impelling means and as a cooling medium, attached therewith to the receiver and wholly independent of, and distinct from, any water removing pump, said air pump being arranged to pump gas, vapor and some liquid from the receiver and to discharge into the separator, an air intake conduit for said pump comprising a pipe for withdrawing gas and vapor mixed with water from the receiver, so that fresh water will be supplied to the seal and the used water caused to be progressively discharged to the separator, a check valve disposed in said conduit, means for eiecting a regulated return of discharge water from the separator to the receiver such that the water level in the receiver is maintained at a substantially constant level, the air pump being submerged to substantially a predetermined depth in the separator water suicient to seal the check valve against the admission of air to the receiver when the pump is idle, and said pump having a submerged 10 water inlet in the bottom of the separator for causing replacement water at atmospheric pressure also to be supplied to the pump directly from the separator, and for causing a predetermined useful amount of water to be contained in the pump at starting.

10. In a vacuum heating system, in combination, a receiver maintained under vacuum, an air separator open to the atmosphere, an air pump in which water is employed as a cooling medium, said pump being arranged to pump gas, vapor and some liquid from the receiver and to discharge into the separator, an air intake conduit for said pump comprising a pipe for withdrawing gas and vapor mixed with water from the receiver, so that fresh Water will be supplied to the pump and progressively discharged to the separator, a check valve disposed in said conduit, Imeans for eiecting a regulated return of discharge water from the separator to the receiver such that the water level in the receiver is maintained at a substantially constant level, the air pump being suiciently submerged in the separator to seal the check valve against the admission of air to the receiver when the pump is idle, and said pump having a submerged water inlet in the bottom of the separator for causing water from a source at atmospheric pressure also to be supplied to the pump directly from the separator, and for causing a predetermined useful amount of water to be contained in the pump at starting.

11. In a vacuum heating system, in combination, a receiver for the system returns, a rotary air pump for evacuating the receiver, said pump being of the liquid ring type in which a centrifugally impelled water ring is employed which serves both as an air impelling means for evacuating the receiver and as a cooling medium, said pump including a principal intake conduit in communication with the receiver, and a separator open to the atmosphere, to which the pump discharges air and water from the receiver and in the bottom of which the pump is disposed, means automatically maintaining the level of the liquid in the separator at a predetermined level so that the pump is submerged to a substantial degree, the pump having a submerged auxiliary inlet passage formed in the pump casing and independent of said intake conduit, and disposed in the bottom of the separator, for causing seal and replacement water to be supplied to the pump directly from the separator at atmospheric pressure.

l2. In a vacuum heating system, in combination, a simple tank partitioned to provide a single receiver chamber which is maintained under vacuum and at least one distinct separator chamber which is maintained under atmospheric pressure, means for conducting the system returns directly -into the receiver, a vacuum pump of the liquid ring type for evacuating the receiver, said pump including a principal intake conduit in communication with the receiver, said pump being disposed in the separator chamber, means automatically maintaining the level of the liquid in the separator at a predetermined level so that the pump is submerged to a predetermined depth, and having a submerged auxiliary inlet opening formed in the pump casing and independent of said intake conduit, and disposed in the bottom of the separator chamber for the direct admission of seal water from a source at atmospheric pressure, said tank having provision for the direct lateral attachment of a large water pump intake conduit, and a water pump located immediately adjacent to the receiver and having a short intake conduit of large flow capacity directly attached to the receiver.

13. In a vacuum heating system, in combination, a tank having partitions for dividing it into a receiver chamber and a plurality of separator chambers, and a plurality of vacuum pumps of the liquid ring type connected to evacuate the receiver chamber, each vacuum pump being arranged to discharge into one of the separator charnbers at atmospheric pressure and each including a principal intake conduit in communication with the receiver means for automatically controlling the return of liquid @essere Y 11 from each separator to the receiver to maintain the liquid in Y the separators at, predetermined levels, and each vacuum pump being submerged in its separator toy a predetermined depthY and having a submerged auxiliary in-v take orifice formed in the pump casing and independent of said intake conduit and disposed in the bottom of the separator, through which make up Water may be drawn. directly fromV the receiver` 14. In a vacuum heating system,V in, combination, a simple tank partitioned to provide a single receiver chamber which is maintained under vacuumV and at least one separator chamber whichk is maintained under atmospheric pressure, means for conducting the system returns directly into the receiver, a vacuum pump of the liquid ring type for evacuating; the receiver,` said pump being disposed in` the separater `chamber means automatically maintaining the level.. of the liquid in the; separator at. zipredetermined, levei so that the pump is submerged to, a predetermined depth, and having a submerged auxiliary inlet openingl formed. in the pumpV casing and, independent of said in.- take conduit, and disposed near the bottom of the sepn arator chamber for the direct. admission of` seal Water from; a source at atmospheric. pressure, said tank' having provision. for the, direct lateral` attachment of a plurality' water pumps may be attached as found desirable or necessary, and atleast one water pump located immediately adf jacent to the receiver and having la short intakel conduit A of largeiiow capacity, directly attached to: the receiver.

References Cited in theV le of this patent I UNITED STATES PATENTS 1,267,897 Pagel May 28, I91'8V 1,449,742 BensonV Mar. 27, 1923' 1,563,904 Kerckhoi et al. Dec. .1, 1925 1,662,250 Iennings Mar. 13, 1926 V1,693,741 Wuest Dec. 4, 1928 1,786,056 Y Durdi'n Dec. 23,. 1930 1,904,321 Nash Apr.. 18, 1933 2,291,760 Rupp Aug. 4,i 1942. 2,306,988 Adama 1360.729, 1942 2,315,945 Durdin Apr. 6, 1943A 2,425,070 Nicolette Aug. 5 1947 V2,439,577 Norton Apr, 13, 1948 2,581,828 Adams Jan. 8,.'1952 2,615,397 Conery O'ct.. 28, 1952 

